The fast-flush device test--based on the square-wave principle--has been used in clinical practice to test the accuracy of fluid-filled pressure-monitoring systems. One assumption with the square-wave test is that the system is a second-order approximation. To elucidate the problem, the authors compared, in vitro, a reference test method (frequency response test), valid for second-order systems, with a pure square-wave test and a fast-flush device test. They showed that the two tested systems did not have any relation to the reference system, which suggests that the second-order approximation is not valid. Therefore, the fast-flush device test cannot be used reliably in testing the total chain of catheter, tubing, transducer, and monitor for invasive pressure measurement.

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Background: Since most intensive care units (ICUs) have no access to high-quality water, the Genius® system, using ultrapure water and high-flux dialyzers, might be used during slow low efficient daily dialysis (SLEDD). To get an idea about convective removal, internal filtration (IF) was calculated and compared to other modalities. Methods: Validated with in vivo measurements, IF was calculated for 8 h Genius® SLEDD and 4 h Genius® standard dialysis with high-flux dialyzers, and for 8 h SLEDD and 4 h both with standard dialysis machines and low-flux as well as high-flux dialyzers. Results: In Genius® SLEDD (FX80), IF was 2.36 l (hematocrit [Hct] 30%) and 3.37 l (Hct 40%). About the same amount of IF was found for the different dialysis modalities, except when using low-flux dialyzers, where no IF occurred. Conclusion: The Genius® system allows the implementation of high-flux dialysis with ultrapure dialysate, and can be run in a SLEDD mode in the ICU.

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Background/Aims: The optimal dose of renal replacement therapy (RRT) in acute renal failure (ARF) is uncertain. Methods: The Randomized Evaluation of Normal versus Augmented Level Replacement Therapy Trial tests the hypothesis that higher dose continuous veno-venous hemodiafiltration (CVVHDF) at an effluent rate of 40 ml/kg/h will increase survival compared to CVVHDF at 25 ml/kg/h of effluent dose. Results: This trial is currently randomizing critically ill patients in 35 intensive care units in Australia and New Zealand with a planned sample size of 1,500 patients. This trial will be the largest trial ever conducted on acute blood purification in critically ill patients. Conclusion: A trial of this magnitude and with demanding technical requirements poses design difficulties and challenges in the logistics, conduct, data collection, data analysis and monitoring. Our report will assist in the development of future trials of blood purification in intensive care. This study was registered with ClinicalTrials.gov (NCT00221013).